<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // ++  自增  递增

    // var age = 18
    // age = age + 1
    // age = age + 1
    // age = age + 1
    // console.log(age)


    var age = 188
    // ++age   // age = age + 1

    // age = ++age + 10  // 189 + 10

    // ++age  // age = age + 1     189
    // + 10

    console.log( ++age + 10 )  // 189 + 10 => 199

    console.log( age )  // ?  189

  </script>
</body>
</html>